It means someday you're gonna meet God and when he inquires as why you didn't take the field against Robinson in Philadelphia and you answer that it's because he was a Negro it may not be a sufficient reply!
Artinya suatu hari nanti kau akan bertemu Tuhan dan ketika dia menanyakan mengapa kau tidak menuju ke lapangan melawan Robinson di Philadelphia dan kau jawab itu karena dia seorang Negro itu bukan jawaban yang memadai!